fix BOARD_CUSTOM_BOOTIMG_MK

Change-Id: Ibaa752979a17343ed3981184129b8c25c5355eb1
Support custom boot/recovery images

Change-Id: I4979d05ca9c23039770b51962e8ff7e066bd0bdc
Remove duplicate vendorsetup.sh processing

Change-Id: I003ebf4768224431c481a7734acccb1bf6cb49f5